1. Field of the Invention
Embodiments of the invention generally relate to implantable biventricular heart therapy devices that detect ventricular tachycardia and fibrillation.
2. Description of the Related Art
Typically, tachycardia identification units allow biventricular detection of tachyarrhythmias, such as ventricular tachycardias (VT) or fibrillations (VF). Generally, therapy device control may initiate suitable therapies based on the detection.
A system known as an S-ICD system typically operates with a far-field channel for VT/VF identification.
For example, a specific type of tachyarrhythmias is “dissimilar” ventricular tachycardias, in which different (beat or contraction) rates prevail in the right ventricle (RV) and in the left ventricle (LV).
Generally, ICD systems available on the market operate exclusively with a right-ventricular VT/VF identification channel. The left-ventricular sensing signals are typically used only for the inhibition of unnecessary LV stimulation and for the recording of an intracardial electrocardiogram (IEGM), but not for VT/VF identification. Based on the observation that there are ventricular tachycardias that have a considerable frequency difference between the right and left ventricle over a considerable period of time, typically, in the event of just right-ventricular detection, there is a potential risk that patients having these dysrhythmias are not being cared for sufficiently.
For example, with a much quicker VT/VF in the left ventricle with a moderate VT in the right ventricle, generally, there is a risk of a lethal appearance of the dysrhythmia, since the time it takes for effective defibrillation is considerably too long as a result of the underestimation only using right-ventricular sensing.
Typically, purely biventricular sensing poses a risk that, for example in the event of a left-ventricular electrode (coronary sinus electrode) dislocated in the region of the atrium, an atrial fibrillation is incorrectly classified as left-ventricular fibrillation (left-VF) and thus leads to an inadequate therapy delivery. A dislocated right-ventricular electrode, generally, may cause a comparable effect.
As such, typically, isolated left-ventricular tachyarrhythmias may be cited as particularly relevant, since they are not generally correctly detected and treated using existing right-ventricular systems. Analyses of biventricular IEGM recordings, generally, reveal a considerable proportion of dysrhythmias of this type.
Known biventricular heart therapy devices are generally inadequate with respect to dissimilar ventricular tachycardias. In view of the above, there is a need for a biventricular heart therapy device, which is able to adequately respond to dissimilar ventricular tachycardias.